A vehicle is installed with a variety of sensors and a controller. The controller may generate false alarms by detecting the operating state of an engine directly after the engine has been started or when a transient condition occurs such as when the pressure of fluids in the engine is rapidly increased.
Regardless of operating modes of the specific engine of the vehicle, since the vehicle installed with an automatic transmission is affected by the oil temperature and the viscosity change of the transmission oil, the hydraulic pressure of the automatic transmission is controlled based on the oil temperature of the automatic transmission oil measured by the oil temperature sensor when the vehicle speed changes.
In order to control overall operations of the automatic transmission by using a transmission control unit (TCU), the automatic transmission includes solenoid valves, installed to a valve body, for controlling the transmission oil passages and the oil temperature sensor. The hydraulic pressure is compensated according to the oil temperature changes by adjusting control signals applied to the solenoid valves alter detection of the oil temperature of the automatic transmission by the oil temperature sensor.
However, since the conventional art is restricted to determination of an electrical fault of the oil temperature sensor for detecting the oil temperature of the automatic transmission, a driver cannot easily manage the situation when the oil temperature sensor has a fault.
Moreover, since the conventional art does not provide a function for detecting the appropriate oil temperature in the valves, wrong information due to the fault of the oil temperature sensor can be utilized as the conditions for determining whether the automatic transmission has a fault or not. For this reason, other faults can be incorrectly detected.